Field of the Invention
The present invention relates to a technical field of medical devices, more particularly to a retractable self-destructing safety syringe with a pre-attached needle, and especially to the mechanical connection structure thereof.
Description of Related Art
Reference Document 1, with Patent No.: ZL200710047077.4, by Application Date: 2007 Oct. 16, with Issued No.: CN101411908, the patentee thereof: Shanghai Dingjiantang Biochemical Technology Co., Ltd., has disclosed a self-destructing safety vaccine syringe comprising a barrel body, a plunger disposed in the barrel body, a rubber piston disposed near an end of the plunger, a needle base disposed in a barrel neck of the barrel body, and a needle disposed on the needle base, which is characterized in that: a lateral notch is formed on a side wall of the end of a plunger body which is interconnected with a vertical notch formed at the end of the plunger body of the plunger and coupled with the vertical notch; an upper needle part and a lower part of the needle base are sleeved together to form the needle base, wherein the lower needle base is cylindrical and has a hollow cavity and a lower needle base rib is disposed on an inner wall of the lower needle base and located near an opening of the end of the lower needle base opposite the end at which the upper needle base is disposed; an elastic member formed by interconnecting the lateral notch with the vertical notch is disposed at the end of the plunger where the plunger body has a specific elasticity, wherein the vertical notch is narrow at the top and wide at the bottom while the outer wall of the plunder body above the outer opening of the lateral notch protrudes beyond an outer wall of the plunger body therebelow, the outer opening of the lateral notch is high and the inner opening thereof is low, and the end of the plunger is in a curved shape; the upper needle base is cylindrical, wherein a plurality of reinforcing fins is disposed on the outer wall of the upper portion of the upper needle base and a flange ring of the upper needle base is disposed on the outer wall of the lower portion of the upper needle base, and the outer diameter of the flange ring of the upper needle base is greater than the diameter of the outer wall of the upper needle base by 0.05 mm to 0.3 mm; the lower needle base is cylindrical and has a hollow cavity, wherein an annular locking groove of the lower needle base is disposed on the inner wall of the cavity of the lower needle base and is coupled with the flange ring of the upper needle base, the inner diameter of the cavity above the annular locking groove of the lower needle base is less than the outer diameter of the outer wall of the plunger body above the flange ring of the upper needle base by 0.1 mm to 0.35 mm while the inner diameter of the cavity below the annular locking groove of the lower needle base is less than or equals to the outer diameter of the outer wall of the plunger body below the flange ring of the upper needle base, and an annular rib of the lower needle base is disposed on the outer wall of an end of the lower needle base opposite the end of the lower needle base rib; an upper stopping ring of the barrel neck and a lower stopping ring of the barrel neck are respectively disposed on the inner wall of the barrel neck of the barrel body And the distance between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck is ranged from 0.3 mm to 1.5 mm, wherein the upper stopping ring of the barrel neck protrudes beyond the inner wall between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck by 0.1 mm to 0.6 mm, the lower stopping ring of the barrel neck protrudes beyond the inner wall between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck by 0.02 mm to 0.25 mm, the inner diameter of the barrel cavity above the upper stopping ring of the barrel neck is greater than or equals to an inner diameter of the barrel cavity between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck while the inner diameter of the barrel cavity between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck is less than or equals to the inner diameter of the barrel cavity below the lower stopping ring of the barrel neck, the inner diameter of the barrel cavity between the upper stopping ring of the barrel neck and the lower stopping ring of the barrel neck is less than the outer diameter of the annular rib of the lower needle base by 0.1 mm to 0.5 mm; a stopping rib of the barrel body is disposed on the inner wall of the barrel cavity at an end opposite the end of the barrel neck and can be a linear annular rib, an annular rib consisting of several vertical ribs, a vertical rib, or an annular rib consisting of multiple protruding points; and an inner rib of the barrel body is disposed on the inner wall of the barrel body below the stopping rib of the barrel body, wherein the distance between the stopping rib of the barrel body and the inner rib of the barrel body is greater than or equals to the thickness of the annular pre-stopper piece and the inner diameter of the stopping rib of the barrel body is smaller than the diameter of the annular pre-stopper piece.
Reference Document 2, with Patent No.: ZL200720067715.4, by Application Date: 2007 Mar. 8, with Issued No.: CN201076648, the patentee thereof: Shanghai Dingjiantang Biochemical Technology Co., Ltd., has disclosed “a plunger with a metal hook” comprising a plunger body, a columnar locking member disposed on an upper end of the plunger body, and a rubber piston sleeved with the columnar locking member, which is characterized in that a mounting hole with a hook inside is disposed on the end of the plunger body at the position corresponding to the rubber piston.
Current safety syringes bear a function of retracting the needle by the hook to realize safe injections. The hook is generally made of metal pieces or plastic pieces. The metal piece requires manufacture process so as to match or be assembled on the plunger. The manufacturing process is complicated and difficult plus uncertainty of stability. Not only are the manufacturing process and cost increased, but the metal piece itself and the assembly process thereof will increase the uncertainty of risks in respect of product safety and quality. The current plastic hook still has structural defects or deficiencies, thereby leading to safety risks or vulnerabilities during use. Though the design of current plastic locking can fulfill the needle-retracting function, the needle still remains on the regular track after being retracted during use, so that it is possible to push out the needle again, which poses a risk of secondary injuries to the user.
In addition, a common problem existing in both current retractable self-destructing safety syringe with a single needle base and the current safety syringes is how to stabilize the locking stability between an inner needle base and a barrel body to the extent satisfying stability requirements, meanwhile the pulling force for retracting the needle base should not be excessive for purpose of user's comfort and convenient use. Although the rigid locking structures can achieve a stable locking effect between the inner needle base and the inner wall of the barrel body, it is hard or even impossible to meet the requirement for convenient use at the same time. The instability of plastic materials and the tendency to be easily affected by environmental temperature lead to poor stability of the products with rigid locking structures, which makes it quite difficult to control the quality and precision during the production process and makes it impossible to realize mass production.
As mentioned above, it is still necessary to further improve the structure of the plunger and the locking structure between the inner needle base and the barrel body of the current retractable syringe, thereby further improving safety and stability during use, and achieving the purposes of simplifying the manufacturing process and reducing the manufacturing cost.